HUBER, D. R. : Comparative Analysis of Methods for Determining Bite Force in the spiny dogfish Squalus Acanthias
One of the critical factors in determining the trophic capabilities of fishes is their generated magnitude of bite force, which can be studied using the biomechanical concept of mechanical advantage and estimates of the maximum tetanic tension (PO) generated by the jaw adductor musculature. To estimate bite force generated by the spiny dogfish Squalus acanthias, the quadratomandibularis (QM) was modeled both as a whole muscle (‘simple’, n=4) and as its individual anterior, posterior, superficial, and ventral heads (‘complex’, n=4), both of which were compared to in situ determinations of bite force measured with a Millar Mikro-Tip catheter pressure transducer (n=9). Within each model, the CSA of each muscle was determined by both measuring digital images of cross-sections (‘measured’) and deriving values from the muscles’ fiber architecture (‘derived’). Standardized theoretical maximum force values from the ‘simple’, ‘complex’, ‘measured’, and ‘derived’ methods differed from the average maximum bite force value from pressure transducer trials by 38.85%, 12.77%, 0.9%, and 10.93% respectively, determining that the ‘complex’ and ‘measured’ methods should be used in conjunction in future study of bite force generation in elasmobranchs. Despite the low range of maximum bite force values obtained from S. acanthias during pressure transducer trials (0.77-19.56N), its effectiveness as a predator is explained in terms of its cranial morphology and ability to extensively protrude the palatoquadrate.
